Cancer patients receiving radiation therapy experience toxic side effects of the radiation, and sensitivity to radiation is variable across both patients and tumors, and is poorly understood. This Phase I SBIR project aims to design and demonstrate the feasibility of a Patient Reported Outcome mobile application for surveillance of RADiotherapy toxicity (PRORAD) that integrates NIH?s Patient Reported Outcomes Common Terminology Criteria for Adverse Events (PRO-CTCAE). Early reporting of toxicities, health related quality of life, and behavioral functionality by patients will enable clinicians to intervene at an earlier stage of symptom development than is currently possible, providing more effective personalized care, as well as support for prospective longitudinal studies to enhance clinical outcomes.PRORAD Phase I will design and demonstrate a prototype mobile app for iOS and/or Android platforms that collects data by guiding radiotherapy patients to accurately selfreport symptom severity based on the PRO-CTCAE.